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A. G. LEIGH.

AEROPLANE.

APPLlcmoM msn sm. n. ma. 1,3 Patented Allg. 19, 1919.

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AEROPLANE.

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ALFREDO GUILLERMO LEIGH, 0F SANTIAGO, CHILE.

AEBOPLANE.

Specication of Letters Patent.

Patented Aug. 19, 1919.

Application ylell September 17, 1918. Serial No. 254,473.

To all rwhom t may concer/n.'

Be it known that I, ALFREDO GUILLERMO Laien, a citizen of the Republic of Chile, and a resident of Santiago, Chile, have invented a new and Improved Aeroplane, of which the following is a full, clear, and exact description.

This invention relates to aero'planes or flying machines of the heavier than air type, and has particular reference to certain novel structural features that serve to make the machine self stabilizing and possessed of other features of advantage.

Among the objects of the invention, therefore, is to provide an aeroplane possessing both inherent lateral stability, and inherent longitudinal stability.

Another object of the invention is to provide an aeroplane having special structuralr features serving to increase the strength and reduce the weight thereof.

Another object of the invention is to reduce the head resistance to the minimum.

Another obiect of the invention is to con struct an aeroplane in which the angle of incidence is variable and regulated by the speed both automatically and at the command of the pilot, enabling him to make the same maneuvers that large birds execute when alighting in a gliding flight.

Another ob]ect of the invention is'to provide an aeroplane capable of alighting in a very small space, and at low speed.

A still further object is to give the pilot absolute control over` the machine so that he is able to maneuver in all ways that are now possible in existing machines, with the added advantage that such operations may be made with greater rapidity, eilicacy, and safety.

Another object of the invention is to so arrange thefuselage as to give the pilot greater range of visibility in all directions.

Owing to the qualities of inherent stabillaterally and longitudinally, I have roved by actual practice in the air tlat it ies perfectly with any wind, no matter how ir la'r the wind may be, and with winds w ose velocities are in proportion to the load carried by the machine. By unity of surface, it is 'possible to stop the motor and with simple maneuvers of direction, realize the sailing flight simulating the flight of-the condor or albatross. In horizontal flights, no matter how stormy the atmosphere, the pilot will only be required to control the rudder so as to guide the machine to the right or to the left. Using gravity as a motor and taking advantage of the force of the wind, it is necessary to direct its course only, this aeroplane maintaining itself and traveling with perfect stability the same as a ship on the ocean..

With the foregoing and other objects in view the invention consists in the arrangement and combination of parts hereinafter described and claimed, and while the invention is not restricted to the exact details of construction disclosed or suggested herein, still for the purpose of illustrating a practical embodiment thereof reference is had to the accompanying drawings, in which like reference characters designate the same parts in the several views, and in which- Figure 1 is a front elevation of fmy improved construction.

Fig. 2 is a plan view of the same.

Fig. 3 is a left side elevation.

Fig. 4 is a front view in diagram illustrative of theV novel principle involved in this construction.

Figs. 5, 6 and 7 are diagrams in side elevation showin the automatic change of position assume by the machine when dropped substantially nose downward; and

Fi 8 is a sectional detail indicati the relation of the auxiliary plane of igh aspect ratio to the main lifti plane, as well as the longitudinal sectona form of the latter plane.

Referring now more specifically to, the vdrawings 10, 10, are two main liftin wings lying essentially in the same horizonta plane, but spaced from each other over the fuselage 11, the space being bridged by meansV of two stream line bars 12 and 13. The inner end portion ofeach wing 10 is curved downward forming a wall 14 which merges into the side wall ofthe fuselage at about be essentially flat, although preferably I from tipto tip of the two i wings. This plane of high aspect ratio may form it cambered upward as shown in Fi 8. The rear or trailing edge 23 of this plane coincides with the vertical plane 24 passing through the front or leading edge 25 of the main or lifting Wings 10. The plane 20 is located below the plane of the wings l() leaving a clear space 26 horizontally between them. Obviously any suitable guys or braces may be employed to hold the parts in operative position, but with such parts l am not particularly concerned except as stated below. This auxiliary plane 20 serves to automatically stabilize the entire machine with respect to the `fore and aft directions, and this plane while being carried in rigid and parallel relation to the main plane 10 may obviously be carried at any desired elevation with respect to the plane of said main plane 1,0 so long as the geometric planes in which the two .planes 10 and 20 are located remain substantially parallel. i

27 indicates the propeller at the front of the fusela e, and with its axis extending .rearward t rough the center of gravity 28 of the machine. At the rear end of the fuselage are located the tailtplane 29, the elevator 30, the fin 31, and the rudder 32 of any suitable .construction and controlled by any suitable devices which per se are not shown since they passin are not of my invention.

By reference to the diagrams in Figs. 5, 6, and 7 the line passing through the center of gravity 28 perpendicular to the lifting planes 10 will intersect the plane of the wings at the point 33. The large arrows in these diagrams indicate the direction, parallel to the lifting surfaces, that an ordinary aeroplane is propelled by reason of the motor or what may be called the center of thrust. In this machine the center of thrust passes through the center of avity. The two points 34 and 35 indicate t e two centers of ressure with respect to the lifting and hig aspect ratio planes. These points are at the rear and in front of the vertical line of the center of gravity respectively. Consideriig themachine as a glider purely and set o or dropped from a certain height and with calm air, its trajectory is ,or may be as shown in Fig. 5 approximately vertical at the beginning, giving to the machine a considerable momentum, but the line of Hight will gradually turn toward the horizontal through the stage indicated in Fig. 6, and nally alighting with an easy perfect landing at a distance equal toat least four times the height of the fall. TheV aerodynamic phenomenon that is produced and that gives origin to the longitudinalinherent equilibrium is explained as f llows: The speed incident to t e rapid fall f the glider causes reactions upward beneath the two planes 10 and 20 at the two centers -o pressure 34 and 35, which are initiated at the same time. The center of pressure 34 opermbst importance is involved in t ates to support the whole, and the front center of pressure 35 acts as a lever upward and around the center of pressure 34 thereby tending to lift the center of gravity which. may be assumed to be suspended from the point 33 until longitudinal equilibrium is established.

Referring now to the diagram in Fig. 4 I have exhibited the special form which gives origin` to the lateral inherent equilibrium whlch is obtained by the combination of three centers of pressure, one central one 34 which for the present consideration may be coincident with the center of pressure of the same number above discussed, and two laterals a and b acting upon the outwardly and upwardly disposed stabilizing planes 36 and 37 extending from the points of lines 21 and 22 respectively, and held fixed or rigid by any suitable means. These planes are indicated as being arranged in the same inclined planes as lateral struts 38 and 39 leading down to the bottom of the fuselage and in substantially a vertical transverse plane of the center of gravity 28 whereby the upper and vouter ends of these struts are located in substantially the transverse line of the point 33 aforesaid. If for instance by reason of a turn or by a gust of wind the aeroplane takes the inclination indicated in dotted lines in Fig. 4 the entire apparatus sli s sidewise in the direction of the arrow. nder these circumstances the upward reaction' on the wing 36 assumed to be exerted at the center of pressure a is superior to the reaction at the center of pressure b and tends to cause a moment in a clock-wise direction in said figure around the center of pressure 34 as a lever, and thereby the normal position of lateral equilibrium is soon established.

With reference now to Fi 8 I wish to point out that the main liting plane is preferably formed with less fore and aft curvature and in the usual practice the plane ribs 40 between the transverse bars 41 and 42 are slightly upwardly cam ed, but back of the bar 42 the planes 10 are substantially flat and terminate at the rear edge 43 in a point that is in line with the bottoms of the ars 41 and 42, and also is in a tangent 44 to the highest point of convexity.

While the high aspect plane 20 is indicated as carnbered or upwardly curved at its lower surface it may be otherwise formed, Likewise the lateral stablilizing planes 36 and 37 might be cambered instead of at as indicated. The one novel feature of construction and advantage that is probably of e fact that I employ to effect the longitudinal inherent stability, the adaptation in tandem `of one or more rigid surfaces of high aspect ratio placed in the front part orpbelow the principal lifting surface in such a way that the distance between the leading or front edge of th-e principal surface and the rear or trailin edge of the surface of high as ect ratio s all not be longer than the chor of said surface of high aspect ratio. That is to say the glane 20 maybe located with its rear edge irectly beneath the front edge of the main plane or in the vertical planeV perpendicular to the main plane, or it may be positioned forward in its own plane to any distance not to exceed the lengt-h of the chord of the plane 20.

1. In an aeroplane, a main lifting plane, a plane of high aspect ratio below and ahead of the leading edge of the lifting plane, and means to hold the plane of high as ect ratio rigid with respect to the mam p ane, and with its rear er trailing edge located at a distance from the leading edge of the main plane not greater than the chord of the plane of high aspect ratio.

2. In an aeroplane, the combination with a main lifting plane, a body and means supporting the body with the center of gravity of the entire structure well below the main plane, of an auxiliary plane of hi hv aspect rat-io below and in front of the leading edge of the main plane, and a pair of lateral stabilizing planes rigidly secured opposite the ends of the main and high aspect ratio planes, the planes being inclined laterally and upward from the ends of the main plane.

3. In an aeroplane, the combination of a plurality of lanes providing a main lifting and an auxi iary lifting surface, the main lifting surface being cambered transversely or in a direction perpendicular to the direction of movement and being of low aspect ratio, while the other plane is straight transversely and of high aspect ratio, a body, and means holding the body in osition with respect to the two surfaces a oresaid as to bring the center of avity below and longitudinally between t e centers of rassure on the two surfaces whereby iniierent longitudinal equilibrium obtains.

4. In an aeroplane, the combination of a main lifting lane, an auxiliary lifting and stabilizin p ane of high aspect ratio entirely in ront of the main plane but spaced forward therefrom a distance not to exceed the chord of the high aspect ratio plane, means extending between the two planes serving to hold them in rigid position with relation to each other in parallel planes one above the other, a body arran d below the planes aforesaid bringing t e center of gravity of the machine below the planes, and means to stabilize the machine laterally.

ALFREDO GUILLERMO LEIGH. 

